Time Dilation Effects of Travel to Star 10ly Away

In summary, the conversation discusses the time difference between an astronaut's measurement of time and the time measured on Earth when traveling at speeds close to the speed of light. It is stated that the time on Earth will be slightly greater than 20 years due to the speed being slightly lower than "c". The topic of General Relativity is brought up, but it is clarified that it is not necessary for this scenario as Special Relativity can handle accelerated motion. GR is only needed for describing gravity.
  • #1
virgil1612
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TL;DR Summary
Astronaut's time versus time measured on Earth.
If an astronaut travels to a 10 ly distant star with a speed very close to light speed, then he will measure a distance to his star much smaller than 10 ly (length contraction) so his time for reaching the star will be smaller than 10 years, let's say 1 year. Then, without delay, he returns back to Earth with the same speed, getting back in 2 years (his time).
When he gets back to Earth, will the time elapsed on Earth be just 20 years (20 ly divided basically by the speed of light), or there are GR implications (presumably because of accelerations), that will produce a different result?
 
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  • #2
GR is not required to analyze this scenario. The time will be slightly greater than 20 years back on Earth since the speed is a little lower than "c", but it will be very close to 20 years on earth.
 
  • #3
virgil1612 said:
Summary:: Astronaut's time versus time measured on Earth.

If an astronaut travels to a 10 ly distant star with a speed very close to light speed, then he will measure a distance to his star much smaller than 10 ly (length contraction) so his time for reaching the star will be smaller than 10 years, let's say 1 year. Then, without delay, he returns back to Earth with the same speed, getting back in 2 years (his time).
When he gets back to Earth, will the time elapsed on Earth be just 20 years (20 ly divided basically by the speed of light), or there are GR implications (presumably because of accelerations), that will produce a different result?

There are a number of places online (and even some textbooks) that say that SR does not cover acceleration and that GR is needed. This is not right. SR can handle accelerated motion. GR describes gravity: i.e. curved spacetime.
 
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Likes vanhees71
  • #4
Great, thank you.
 

1. What is time dilation and how does it relate to travel?

Time dilation is a phenomenon in which time appears to pass slower for an object in motion compared to a stationary object. This is due to the effects of special relativity, which states that the speed of light is constant and the laws of physics are the same for all observers in uniform motion.

2. How does traveling to a star 10 light years away affect time dilation?

Traveling to a star 10 light years away would result in a significant time dilation effect. This is because the speed of light is the fastest speed possible, so the closer an object travels to the speed of light, the slower time appears to pass for that object. Therefore, the longer the distance traveled, the greater the time dilation effect will be.

3. How is time dilation measured and quantified?

Time dilation is measured by comparing the time experienced by an object in motion to the time experienced by a stationary object. This can be quantified using the Lorentz factor, which is a mathematical formula that takes into account the speed of the object and the speed of light to determine the amount of time dilation.

4. What are some real-life examples of time dilation effects?

Time dilation effects have been observed in various experiments, such as the famous Hafele-Keating experiment where atomic clocks were flown around the world and compared to stationary clocks. The clocks on the planes, which were traveling at high speeds, were found to be slightly behind the stationary clocks due to time dilation. GPS satellites also have to account for time dilation in order to accurately determine location.

5. What are the implications of time dilation for space travel?

Time dilation has significant implications for space travel, as it means that time will pass slower for astronauts traveling at high speeds. This could potentially lead to astronauts experiencing less aging compared to their counterparts on Earth. It also means that long-distance space travel would require careful planning and consideration of time dilation effects in order to accurately measure and track time.

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